Controlling data consistency guarantees in storage apparatus
First Claim
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1. A peer-to-peer storage system comprising:
- a plurality of peer-to-peer storage nodes, each peer-to-peer storage node storing a copy of data such that the copy of the data has a consistency guarantee across the peer-to-peer storage system in that regardless of which peer-to-peer storage node from which the copy of the data is retrieved, the copy of the data is identical;
a consistency freeze/thaw component at each peer-to-peer storage node, responsive to an indication of a communication failure between any two peer-to-peer storage nodes of the plurality of peer-to-peer storage nodes, to initiate a consistency freeze action in which the copy of the data is maintain at a current state and is not permitted to change,wherein the consistency freeze action is initiated responsive to the indication of the communication failure prior to expiration of a current group lease period concerning at least the copy of the data,wherein the consistency freeze action is initiated by the consistency freeze/thaw component at each peer-to-peer storage node under a timing constraint related to local clocks at the peer-to-peer storage nodes without a common system clock of the peer-to-peer storage system as a whole,and wherein the timing constraint takes into account a worst-case time difference among the local clocks due at least to varying local clock rate drifts and local lock rate jitter.
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Abstract
An apparatus, method and computer program operable in a network controls consistency guarantees of a plurality of data copies in a storage apparatus, and includes: a lease control component for extending a lease to the storage apparatus; and a consistency freeze/thaw component responsive to a failure indication for initiating a consistency freeze action at the storage apparatus prior to expiration of the current group lease period. It may further include a timer component for waiting the apparatus for a predetermined period after the consistency freeze action, where the consistency freeze/thaw component is operable to initiate a thaw action at the storage apparatus.
18 Citations
20 Claims
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1. A peer-to-peer storage system comprising:
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a plurality of peer-to-peer storage nodes, each peer-to-peer storage node storing a copy of data such that the copy of the data has a consistency guarantee across the peer-to-peer storage system in that regardless of which peer-to-peer storage node from which the copy of the data is retrieved, the copy of the data is identical; a consistency freeze/thaw component at each peer-to-peer storage node, responsive to an indication of a communication failure between any two peer-to-peer storage nodes of the plurality of peer-to-peer storage nodes, to initiate a consistency freeze action in which the copy of the data is maintain at a current state and is not permitted to change, wherein the consistency freeze action is initiated responsive to the indication of the communication failure prior to expiration of a current group lease period concerning at least the copy of the data, wherein the consistency freeze action is initiated by the consistency freeze/thaw component at each peer-to-peer storage node under a timing constraint related to local clocks at the peer-to-peer storage nodes without a common system clock of the peer-to-peer storage system as a whole, and wherein the timing constraint takes into account a worst-case time difference among the local clocks due at least to varying local clock rate drifts and local lock rate jitter. - View Dependent Claims (2, 3, 4, 5)
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6. A peer-to-peer storage node of a peer-to-peer storage system including a plurality of peer-to-peer storage nodes including the peer-to-peer storage node, comprising:
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a storage device to store a copy of data such that the copy of the data has a consistency guarantee across the peer-to-peer storage system in that regardless of which peer-to-peer storage node of the peer-to-peer storage system from which the copy of the data is retrieved, the copy of the data is identical; a consistency freeze/thaw component, responsive to an indication of a communication failure between the peer-to-peer storage node and another peer-to-peer storage node of the peer-to-peer storage system, to initiate a consistency freeze action in which the copy of the data is maintain at a current state and is not permitted to change, wherein the consistency freeze action is initiated responsive to the indication of the communication failure prior to expiration of a current group lease period concerning at least the copy of the data, wherein the consistency freeze action is initiated by the consistency freeze/thaw component at the peer-to-peer storage node under a timing constraint related to local clocks at the peer-to-peer storage nodes without a common system clock of the peer-to-peer storage system as a whole, and wherein the timing constraint takes into account a worst-case time difference among the local clocks due at least to varying local clock rate drifts and local lock rate jitter. - View Dependent Claims (7, 8, 9, 10)
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11. A method comprising:
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at each peer-to-peer storage node of a plurality of peer-to-peer storage nodes of a peer-to-peer storage system, storing a copy of data such that the copy of the data has a consistency guarantee across the peer-to-peer storage system in that regardless of which peer-to-peer storage node from which the copy of the data is retrieved, the copy of the data is identical; and at each peer-to-peer storage node, responsive to an indication of a communication failure between any two peer-to-peer storage nodes of the plurality of peer-to-peer storage nodes, initiating a consistency freeze action in which the copy of the data is maintain at a current state and is not permitted to change, wherein the consistency freeze action is initiated responsive to the indication of the communication failure prior to expiration of a current group lease period concerning at least the copy of the data, wherein the consistency freeze action is initiated by the consistency freeze/thaw component at each peer-to-peer storage node under a timing constraint related to local clocks at the peer-to-peer storage nodes without a common system clock of the peer-to-peer storage system as a whole, and wherein the timing constraint takes into account a worst-case time difference among the local clocks due at least to varying local clock rate drifts and local lock rate jitter. - View Dependent Claims (12, 13, 14, 15)
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16. An article of manufacture for a peer-to-peer storage node of a peer-to-peer storage system including a plurality of peer-to-peer storage nodes including the peer-to-peer storage node, comprising:
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a non-transitory computer-readable medium; and means in the medium for, responsive to an indication of a communication failure between the peer-to-peer storage node and another peer-to-peer storage node of the peer-to-peer storage system, initiating a consistency freeze action in which the copy of the data is maintain at a current state and is not permitted to change, wherein the consistency freeze action is initiated responsive to the indication of the communication failure prior to expiration of a current group lease period concerning at least the copy of the data, wherein the consistency freeze action is initiated by the consistency freeze/thaw component at the peer-to-peer storage node under a timing constraint related to local clocks at the peer-to-peer storage nodes without a common system clock of the peer-to-peer storage system as a whole, wherein the timing constraint takes into account a worst-case time difference among the local clocks due at least to varying local clock rate drifts and local lock rate jitter, and wherein the peer-to-peer storage node is to store a copy of data such that the copy of the data has a consistency guarantee across the peer-to-peer storage system in that regardless of which peer-to-peer storage node of the peer-to-peer storage system from which the copy of the data is retrieved, the copy of the data is identical. - View Dependent Claims (17, 18, 19, 20)
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Specification